Dispersible fiber bundles and suspensions using environmentally-friendly solvents

ABSTRACT

Methods of preparing dispersible fiber bundles comprising contacting a rheology-modifying binder to at least two or more fibers to form a binder-fiber mixture, and imparting force to the binder-fiber mixture to compact the binder-fiber mixture into a fiber bundle.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional PatentApplication No. 61/774,956 filed Mar. 8, 2013, incorporated herein byreference in its entirety.

FIELD OF THE INVENTION

This invention relates to products, methods and processes related todispersing fiber bundles in environmentally friendly solvents andrelated applications.

BACKGROUND OF THE INVENTION

Cut staple fibers are used in a variety of applications ranging fromtextiles, non-wovens, carpets, upholstery, filters, reinforcements forcomposites, or even hydraulic fracturing among many others. In all ofthese applications the dry staple fibers are difficult to handle due tothe large volume of randomly oriented high aspect ratio cylinders, andtheir ability to get airborne often posing even an inhalation hazard(e.g. asbestos, glass fibers, and even polymeric fibers). These highvolume fibers are usually costly to ship (in bulk) even if they aresomewhat compacted in bales, but still need to be handled at the pointof use. It also poses a problem for effectively metering the amount offiber for any given industrial operation.

In many of the applications, to facilitate handling, the fibers are usedas suspensions in aqueous, solvent or polymeric/resin media. In order tomake the fiber suspensions, they are manually added from bags intomixing tanks with low process control. Effective mixing is required forproper dispersion, especially with glass fibers in organic media orhydrophobic fibers in water, where they have a natural tendency tocluster. Dispersing aids may be employed. There is also a need to add arheology modifier to the suspension in order to be able to pump thesuspension. In the absence of rheology control to transfer the shearstress to the fibers, the fibers simply tend to bridge with liquiddrainage through a plug of fibers.

Thus, there is need to effectively manage the delivery and handling ofshort staple fibers especially when they need to be suspended in aliquid at the point of use.

SUMMARY OF INVENTION

Described herein are solutions related to managing volume issue forhandling polymer fibers, and in particular, short staple fibers or cutstaple fibers. In one embodiment, the polymer fibers are hydrophobicpolymer fibers. In one embodiment, one solution includes compacting thestaple fibers into bundles using an adhesive or binder.

In one aspect described herein are methods of preparing dispersiblefiber bundles comprising contacting a rheology-modifying binder to atleast two or more fibers to form a binder-fiber mixture, and impartingforce to the binder-fiber mixture to compact the binder-fiber mixtureinto a fiber bundle.

In another aspect, described herein are methods of preparing dispersiblefiber bundles comprising: contacting a rheology-modifying binder with atleast two or more fibers to form a binder-fiber mixture; and impartingforce to the binder-fiber mixture to substantially orient the at leasttwo fibers in a first direction, thereby forming a fiber bundle. In oneembodiment, the rheology-modifying binder is selected from at least oneguar, at least one derivatized guar, at least one cellulose, at leastone modified cellulose (e.g. hydroxyl ethyl cellulose, hydroxyl methylcellulose), at least one acrylate, at least one viscoelastic surfactant,or any combination thereof. The fibers can be oriented in asubstantially longitudinal direction. The method further includessevering the fiber bundle into two or more shorter length fiber bundles.

In another aspect, described herein are methods of preparing adispersible fiber bundle slurry comprising: contacting arheology-modifying binder to at least two or more fibers to form abinder-fiber mixture, imparting force to the binder-fiber mixture tosubstantially orient the at least two fibers in a first direction,thereby forming a fiber bundle; and contacting the fiber bundle with asolvent blend, the solvent blend comprising at least one of thefollowing components:

a) dialkyl methylglutarate;

b) a first blend of: dialkyl methylglutarate, dialkyl ethylsuccinateand, optionally, dialkyl adipate;

c) a second blend of: dialkyl adipate, dialkyl glutarate and dialkylsuccinate;

d) a dioxolane compound of formula I:

wherein R6 and R7, which may be identical or different, is individuallya hydrogen, an alkyl group, an alkenyl group, or a phenyl group, whereinn is an integer of from 1 to 10; and

e) a compound or mixture of compounds having formula (II):

R₃OOC-A-CONR₄R₅  (II),

wherein R₃ is a group chosen from saturated or unsaturated, linear orbranched, optionally cyclic, optionally aromatic hydrocarbon-basedgroups comprising an average number of carbon atoms ranging from 1 to36; wherein R₄ and R₅, which are identical or different, are groupschosen from saturated or unsaturated, linear or branched, optionallycyclic, optionally aromatic, optionally substituted hydrocarbon-basedgroups comprising an average number of carbon atoms ranging from 1 to36, it being possible for R4 and R5 to optionally together form a ring,that is optionally substituted; and wherein A is a linear or brancheddivalent alkyl group comprising an average number of carbon atomsranging from 2 to 12.

In another aspect, described herein are fiber bundles comprising: atleast two polymer fibers; and a rheology-modifying binder comprising atleast one guar, at least one derivatized guar, at least one cellulose,at least one modified cellulose, at least one acrylate, at least oneviscoelastic surfactant, or any combination thereof, wherein the fibersare treated with an effective amount of the binder to enhance thecohesion of the fiber bundle.

In another aspect, described herein are fiber bundle slurries comprising(1) a fiber bundle comprising: (a) at least two polymer fibers; and (b)a rheology-modifying binder comprising at least one guar, at least onederivatized guar, at least one cellulose, at least one modifiedcellulose, at least one acrylate, at least one viscoelastic surfactant,or any combination thereof, wherein the fibers are treated with aneffective amount of the binder to enhance the cohesion of the fiberbundle; and (2) a solvent blend comprising at least one of the followingcomponents:

a) dialkyl methylglutarate;

b) a first blend of: dialkyl methylglutarate, dialkyl ethylsuccinateand, optionally, dialkyl adipate;

c) a second blend of: dialkyl adipate, dialkyl glutarate and dialkylsuccinate;

d) a dioxolane compound of formula I:

wherein R6 and R7, which may be identical or different, is individuallya hydrogen, an alkyl group, an alkenyl group, or a phenyl group, whereinn is an integer of from 1 to 10; and

e) a compound or mixture of compounds having formula (II):

R3OOC-A-CONR4R5  (II),

wherein R3 is a group chosen from saturated or unsaturated, linear orbranched, optionally cyclic, optionally aromatic hydrocarbon-basedgroups comprising an average number of carbon atoms ranging from 1 to36; wherein R4 and R5, which are identical or different, are groupschosen from saturated or unsaturated, linear or branched, optionallycyclic, optionally aromatic, optionally substituted hydrocarbon-basedgroups comprising an average number of carbon atoms ranging from 1 to36, it being possible for R4 and R5 to optionally together form a ring,that is optionally substituted; and wherein A is a linear or brancheddivalent alkyl group comprising an average number of carbon atomsranging from 2 to 12.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a photograph illustrating hydrophobic polymer fibers indifferent solvents, displaying dispersion behavior.

FIG. 2 is a photograph illustrating Compaction of hydrophobic polymerfibers into bundles using a guar solution followed by drying.

FIG. 3( a) is a photograph illustrating hydrophobic polymer-guar bundleshydrated and dispersed in water, side view.

FIG. 3( b) is a photograph illustrating hydrophobic polymer-guar bundleshydrated and dispersed in water, top view.

FIG. 4( a) is a photograph of compact hydrophobic polymer fiber bundles(10-12 mm spheres).

FIG. 4( b) is a photograph of compact hydrophobic polymer fiber bundles(7-9 mm spheres).

FIG. 4( c) is a photograph of compact hydrophobic polymer fiber(cylindrical shape).

FIG. 4( d) is a photograph of compact hydrophobic polymer fiber(cylindrical shape cut longitudinally into pieces).

FIG. 5( a) is a photograph of 10% w/w of 7-9 mm hydrophobic polymerspherical bundles (11.5% binder) suspended in dioxolane solvent-claypremix

FIG. 5 (b) is a photograph of 15% w/w of 6-8 mm cylinders (11.5% binder)suspended in a Rhodiasolv® Polarclean-clay premix.

FIG. 5 (c) is a photograph of hydrophobic polymer bundles suspended inthe solvent-clay medium, illustrating flow properties.

DETAILED DESCRIPTION OF INVENTION

As used herein, the term “alkyl” means a saturated straight chain,branched chain, or cyclic hydrocarbon radical, including but not limitedto, methyl, ethyl, n-propyl, iso-propyl, n-butyl, sec-butyl, t-butyl,pentyl, n-hexyl, and cyclohexyl.

As used herein, the term “aryl” means a monovalent unsaturatedhydrocarbon radical containing one or more six-membered carbon rings inwhich the unsaturation may be represented by three conjugated doublebonds, which may be substituted one or more of carbons of the ring withhydroxy, alkyl, alkenyl, halo, haloalkyl, or amino, including but notlimited to, phenoxy, phenyl, methylphenyl, dimethylphenyl,trimethylphenyl, chlorophenyl, trichloromethylphenyl, aminophenyl, andtristyrylphenyl.

As used herein, the term “alkylene” means a divalent saturated straightor branched chain hydrocarbon radical, such as for example, methylene,dimethylene, trimethylene.

As used herein, the terminology “(Cr-Cs)” in reference to an organicgroup, wherein r and s are each integers, indicates that the group maycontain from r carbon atoms to s carbon atoms per group.

As used herein, the terminology “surfactant” means a compound that whendissolved in an aqueous medium lowers the surface tension of the aqueousmedium.

Described herein are water dispersible fiber bundles, methods ofpreparing the water dispersible fiber bundles and methods of dispersingthe described fiber bundles in solution. Also described herein areprocesses to disperse or suspend polymer fibers, in particular, shortstaple fibers without the use special mixing equipment, which are verytime-consuming and costly. In particular, described herein is the use ofone or more water soluble rheology modifiers as a binder (or a componentof the binder) to prepare staple fiber bundles, typically cut polymerfiber bundles. It has been surprisingly found that the treatment ofshort-cut polymer fibers with selected binders described herein leads tofiber bundles or pellets capable of being disperses more effectivelyinto an aqueous matrix. It is understood that the term “bundles”incorporates any compact shape or form of fibers, including but notlimited to bundles, pellets, clusters, bunches, clumps, mass, rolls,chunks, rods, arrangements, aggregations, assemblages or the like.

In one embodiment, the water soluble rheology modifier comprises apolysaccharide or modified polysaccharide. In one embodiment, thepolysaccharide or modified polysaccharide comprises guar, derivatizedguar, cellulose, modified cellulose, including but not limited tohydroxypropyl cellulose, hydroxymethyl cellulose, hydroxyl ethylcellulose, acrylate, viscoelastic surfactant, or a combination thereof.In some embodiments the rheology-modifying binder is at least one guar,at least one guar derivative, or a combination thereof. In someembodiment, the rheology-modifying binder is at least one viscoelasticsurfactant, or a combination of two or more viscoelastic surfactants.

The modified cellulose can include, for example, cationically modifiedcellulose derivatives containing hydroxy groups such as, cationicallymodified cellulose, cationically modified hydroxyl alkyl cellulose, suchas hydroxyethyl cellulose and the like.

The fibers, or fiber bundles can be used in conjunction with otherpolymers and surfactants. In one embodiment, the fibers may be celluloseacetate, polyamide, PLA or PGA, PEEK, acrylic, polyester, glass, metal,inorganic, or any other non-water soluble fiber. In another embodiment,the fibers are selected from poly-3-hydroxybutyrate (PHB),polyhydroxyalkanoates (PHA), Polyamide 11 (PA 11) or the like. Inanother embodiment, the polymer fiber is non-water soluble orpartially-water soluble. When these fiber bundles are hydrated the watersoluble binder quickly dissolves, rapidly dispersing the fibers whilebuilding viscosity to shear and disperse the fibers more effectivelyinto the aqueous matrix. This viscous suspension can then be pumpedwithout the liquid drainage, bridging and clogging issues.

In one embodiment, the fibers have a staple length of from 1 to 50 mm.In another embodiment the fibers have a staple length of from 2 to 24mm. In another embodiment the fibers have a staple length of from 3 to20 mm. In a further embodiment the fibers have a staple length of from 6to 12 mm. In another embodiment the fibers have a staple length ofgreater than 1 mm, or 2 mm, or 4 mm or 5 mm or 6 mm or 8 mm. In anotherembodiment the fibers have a staple length of greater than 4 mm. Inanother embodiment the fibers have a staple length of greater than 5 mm.In yet another embodiment the fibers have a staple length of greaterthan 6 mm. In another embodiment the fibers have a staple length ofgreater than 8 mm. In another embodiment the fibers have a staple lengthof greater than 10 mm. In another embodiment the fibers have a staplelength of greater than 12 mm. In another embodiment the fibers have astaple length of greater than 14 mm. In another embodiment the fibershave a staple length of greater than 15 mm. In another embodiment thefibers have a staple length of greater than 20 mm. In some embodiments,staple length is the longitudinal length of a piece of cylindrical fiberthat has been cut or severed perpendicular to its longitudinal axis.

In some embodiments, the fiber bundle or polymer fibers have an averagestaple length of at least 0.5 mm, at least 1 mm, at least 2 mm, at least3 mm, at least 4 mm, at least 5 mm, or at least 6 mm or at least 10 mm,or at least 15 mm.

The rheology-modifying binder, in one embodiment, is selected fromxanthans, such as xanthan gum, polyfructoses such as levan, andgalactomannans such as guar gum, locust bean gum, tara gum, or acombination of any of the foregoing.

In one embodiment, the polysaccharide is a locust bean gum. Locust beangum or carob bean gum is the refined endosperm of the seed of the carobtree, Ceratonia siliqua. The ratio of galactose to mannose for this typeof gum is about 1:4. In one embodiment, the polysaccharide is a taragum. Tara gum is derived from the refined seed gum of the tara tree. Theratio of galactose to mannose is about 1:3.

In one embodiment, the polysaccharide is a polyfructose. Levan is apolyfructose comprising 5-membered rings linked through β-2,6 bonds,with branching through β-2,1 bonds. Levan exhibits a glass transitiontemperature of 138° C. and is available in particulate form. At amolecular weight of 1-2 million, the diameter of the densely-packedspherulitic particles is about 85 nm.

In one embodiment, the polysaccharide is a xanthan. Xanthans of interestare xanthan gum and xanthan gel. Xanthan gum is a polysaccharide gumproduced by Xathomonas campestris and contains D-glucose, D-mannose,D-glucuronic acid as the main hexose units, also contains pyruvate acid,and is partially acetylated.

In one embodiment, the polysaccharide of the present invention isderivatized or non-derivatized guar. Guar comes from guar gum, themucilage found in the seed of the leguminous plant Cyamopsistetragonolobus. The water soluble fraction (85%) is called “guaran,”which consists of linear chains of (1,4)-.β-D mannopyranosyl units-withα-D-galactopyranosyl units attached by (1,6) linkages. The ratio ofD-galactose to D-mannose in guaran is about 1:2.

The guar seeds used to make guar gum are composed of a pair of tough,non-brittle endosperm sections, hereafter referred to as “guar splits,”between which is sandwiched the brittle embryo (germ). After dehulling,the seeds are split, the germ (43-47% of the seed) is removed byscreening. The splits typically contain about 78-82% galactomannanpolysaccharide and minor amounts of some proteinaceous material,inorganic salts, water-insoluble gum, and cell membranes, as well assome residual seedcoat and seed embryo.

In one embodiment, the rheology-modifying binder is selected from guaror derivatized guar.

In one embodiment, the guar is native guar, unwashed guar gum, washedguar gum, or a combination thereof. In one embodiment, the derivatizedguar is cationic guar, carboxymethyl guar (CM guar), hydroxyethyl guar(HE guar), hydroxypropyl guar (HP guar), carboxymethylhydroxypropyl guar(CMHP guar), cationic guar, hydrophobically modified guar (HM guar),hydrophobically modified carboxymethyl guar (HMCM guar), hydrophobicallymodified hydroxyethyl guar (HMHE guar), hydrophobically modifiedhydroxypropyl guar (HMHP guar), cationic hydrophobically modifiedhydroxypropyl guar (cationic HMHP guar), hydrophobically modifiedcarboxymethylhydroxypropyl guar (HMCMHP guar), hydrophobically modifiedcationic guar (HM cationic guar), guar hydroxypropyl trimonium chloride,hydroxypropyl guar hydroxypropyl trimonium chloride, or a combination ofany of the foregoing.

In another embodiment, the rheology-modifying binder is a viscoelasticsurfactant or a combination of viscoelastic surfactants

The viscoelastic surfactants include zwitterionic surfactants and/oramphoteric surfactants and cationic surfactants. A zwitterionicsurfactant has a permanently positively charged moiety in the moleculeregardless of pH and a negatively charged moiety at alkaline pH. Acationic surfactant has a positively charged moiety regardless of pH. Anamphoteric surfactant has both a positively charged moiety and anegatively charged moiety over a certain pH range (e.g., typicallyslightly acidic), only a negatively charged moiety over a certain pHrange (e.g., typically slightly alkaline) and only a positively chargedmoiety at a different pH range (e.g., typically moderately acidic).

In one embodiment, the cationic surfactant is selected from i) certainquaternary salts and ii) certain amines, iii) amine oxide, iv) andcombinations thereof.

The quaternary salts have the structural formula:

wherein R₁ is a hydrophobic moiety of alkyl, alkylarylalkyl,alkoxyalkyl, alkylaminoalkyl or alkylamidoalkyl. R₁ has from about 18 toabout 30 carbon atoms and may be branched or straight-chained andsaturated or unsaturated. Representative long chain alkyl groups includeoctadecentyl (oleyl), octadecyl (stearyl), docosenoic (erucyl) and thederivatives of tallow, coco, soya and rapeseed oils. The preferred alkyland alkenyl groups are alkyl and alkenyl groups having from about 18 toabout 22 carbon atoms.

R₂, R₃, and R₅ are, independently, an aliphatic group having from 1 toabout 30 carbon atoms or an aromatic group having from 7 to about 15carbon atoms. The aliphatic group typically has from 1 to about 20carbon atoms, more typically from 1 to about 10 carbon atoms, and mosttypically from 1 to about 6 carbon atoms. Representative aliphaticgroups include alkyl, alkenyl, hydroxyalkyl, carboxyalkyl, andhydroxyalkyl-polyoxyalkylene. The aliphatic group can be branched orstraight-chained and saturated or unsaturated. Preferred alkyl chainsare methyl and ethyl. Preferred hydroxyalkyls are hydroxyethyl andhydroxypropyl. Preferred carboxyalkyls are acetate and propionate.Preferred hydroxyalkyl-polyoxyalkylenes are hydroxyethyl-polyoxyethyleneand hydroxypropyl-polyoxypropylene. Examples of aromatic moietiesinclude cyclic groups, aryl groups, and alkylaryl groups. A preferredalkylaryl is benzyl.

X is suitable anion, such as Cl⁻, Br⁻, and (CH₃)₂SO4⁻.

Representative quaternary salts of the above structure includemethylpolyoxyethylene(12-18)octadecanammonium chloride,methylpolyoxyethylene(2-12)cocoalkylammonium chloride, andisotridecyloxypropyl polyoxyethylene (2-12) methyl ammonium chloride.

The amines have the following structural formula:

wherein R₁, R₂, and R₃ are as defined above.

Representative amines of the above structure includepolyoxyethylene(2-15)cocoalkylamines,polyoxyethylene(12-18)tallowalkylamines, andpolyoxyethylene(2-15)oleylamines.

Selected zwitterionic surfactants are represented by the followingstructural formula:

wherein R₁ is as described above. R₂ and R₃ are, independently, analiphatic moiety having from 1 to about 30 carbon atoms or an aromaticmoiety having from 7 to about 15 carbon atoms. The aliphatic moietytypically has from 1 to about 20 carbon atoms, more typically from 1 toabout 10 carbon atoms, and most typically from 1 to about 6 carbonatoms. The aliphatic group can be branched or straight chained andsaturated or unsaturated. Representative aliphatic groups include alkyl,alkenyl, hydroxyalkyl, carboxyalkyl, and hydroxyalkyl-polyoxyalkylene.Preferred alkyl chains are methyl and ethyl. Preferred hydroxyalkyls arehydroxyethyl and hydroxypropyl. Preferred carboxyalkyls are acetate andpropionate. Preferred hydroxyalkyl-polyoxyalkylenes arehydroxyethyl-polyoxyethylene or hydroxypropyl-polyoxypropylene). R₄ is ahydrocarbyl radical (e.g. alkylene) with chain length 1 to 4 carbonatoms. Preferred are methylene or ethylene groups. Examples of aromaticmoieties include cyclic groups, aryl groups, and alkylaryl groups. Apreferred arylalkyl is benzyl.

Specific examples of selected zwitterionic surfactants include thefollowing structures:

wherein R₁ is as described above.

Other representative zwitterionic surfactants include dihydroxyethyltallow glycinate, oleamidopropyl betaine, and erucyl amidopropylbetaine.

Selected amphoteric surfactants useful in the viscoelastic surfactantfluid of the present invention are represented by the followingstructural formula:

wherein R₁, R₂, and R₄ are as described above.

Specific examples of amphoteric surfactants include those of thefollowing structural formulas:

wherein R₁ is as described above. X⁺ is an inorganic cation such as Na⁺,K⁺, NH₄ ⁺ associated with a carboxylate group or hydrogen atom in anacidic medium.

The selected zwitterionic and amphoteric surfactants are functionallyinterchangeable and may be used separately or alone (alternatively) orin combination with each other.

The fiber bundles can include (in either the product, process of makingor during dispersion into solution), various other additives.Non-limiting examples include stabilizers, thickeners, corrosioninhibitors, mineral oils, enzymes, ion exchangers, chelating agents,dispersing agents and the like. In one particular embodiment, fiberbundles can include (in either the product, process of making or duringdispersion into solution), polyacrylates, polyDADMAC [poly(diallyldimethyl ammonium chloride] and combinations thereof), and clay(Bentonite and attapulgite).

A guar solution was utilized to bind hydrophobic polymer fibers togetherin spherical and cylindrical bundles, which was observed to disperserapidly when mixed in water. Guar is especially effective in lowconcentrations as it hydrates and builds viscosity rapidly. This couplesthe fibers and rheology modifiers into a packaged solution whileaddressing most issues in handling of staple fibers. In such anembodiment, it is not necessary to separately add a viscosity builderfor any suitable industrial application, including hydraulic fracturingapplication. (In some embodiments, it may be useful, however, to add aviscosity builder or other additive.) It dramatically reduces the volumeoccupied by the fiber, handling issues, and transportation cost. Thesebundles may be metered and conveyed pneumatically.

As described above, there are also existing problems associated in thetransportation and handling of bulk dry staple fibers, and in particularin the end use handling in suitable industrial applications, e.g.,textile industry. In many instances, it is preferable to load aningredient to a mixture into a loading tank and pump it to a mixingtank. However, this is not feasible sometimes, when ingredients areshipped in dry bulk form, and an operator would likely have to manuallyadd it by hand, which introduces variables such as human error. In oneembodiment, described herein are compositions and products that includethe fiber bundles as described herein suspended in a solvent to form aslurry. The fiber bundles, in this slurry or liquid form, can easily bepumped and metered into tanks such as loading tanks, as well as to andfrom other tanks. The solvent can be, in some embodiments, anenvironmentally-friendly solvent that is at least partiallybiodegradable or has a favorable eco-toxicity profile (as compared withcommonly used solvents in the industry). Typically, the solvent orsolvent mixture is chosen such that neither the water soluble binder northe polymeric staple fibers are soluble in the solvent to an appreciabledegree.

In one embodiment, the solvent or solvent blend is chosen from at leastone of the following components, below:

a) dialkyl methylglutarate;

b) a first blend of: dialkyl methylglutarate, dialkyl ethylsuccinateand, optionally, dialkyl adipate;

c) a second blend of: dialkyl adipate, dialkyl glutarate and dialkylsuccinate;

d) a dioxolane compound of formula I:

wherein R6 and R7, which may be identical or different, is individuallya hydrogen, an alkyl group, an alkenyl group, a phenyl group, wherein nis an integer of from 1 to 10;

e) a compound or mixture of compounds having formula (II):

R₃OOC-A-CONR₄R₅  (II),

wherein R₃ is a group chosen from saturated or unsaturated, linear orbranched, optionally cyclic, optionally aromatic hydrocarbon-basedgroups comprising an average number of carbon atoms ranging from 1 to36; wherein R₄ and R₅, which are identical or different, are groupschosen from saturated or unsaturated, linear or branched, optionallycyclic, optionally aromatic, optionally substituted hydrocarbon-basedgroups comprising an average number of carbon atoms ranging from 1 to36, it being possible for R₄ and R₅ to optionally together form a ring,that is optionally substituted and/or that optionally comprises aheteroatom; and wherein A is a linear or branched divalent alkyl groupcomprising an average number of carbon atoms ranging from 2 to 12,typically from 2 to 4;

In one embodiment, the solvent blend is selected for a blend of dibasicesters. Dibasic esters of the present invention may be derived from oneor more by-products in the production of polyamide, for example,polyamide 6,6. In one embodiment, the cleaning composition comprises ablend of linear or branched, cyclic or noncyclic, C1-C20 alkyl, aryl,alkylaryl or arylalkyl esters of adipic diacids, glutaric diacids, andsuccinic diacids. In another embodiment, the cleaning compositioncomprises a blend of linear or branched, cyclic or noncyclic, C1-C20alkyl, aryl, alkylaryl or arylalkyl esters of adipic diacids,methylglutaric diacids, and ethylsuccinic diacids

Generally, polyamide is a copolymer prepared by a condensation reactionformed by reacting a diamine and a dicarboxylic acid. Specifically,polyamide 6,6 is a copolymer prepared by a condensation reaction formedby reacting a diamine, typically hexamethylenediamine, with adicarboxylic acid, typically adipic acid.

In one embodiment, the blend of dibasic esters can be derived from oneor more by-products in the reaction, synthesis and/or production ofadipic acid utilized in the production of polyamide, the cleaningcomposition comprising a blend of dialkyl esters of adipic diacids,glutaric diacids, and succinic diacids (herein referred to sometimes as“AGS” or the “AGS blend”).

In one embodiment, the blend of esters is derived from by-products inthe reaction, synthesis and/or production of hexamethylenediamineutilized in the production of polyamide, typically polyamide 6,6. Thecleaning composition comprises a blend of dialkyl esters of adipicdiacids, methylglutaric diacids, and ethylsuccinic diacids (hereinreferred to sometimes as “MGA”, “MGN”, “MGN blend” or “MGA blend”).

In certain embodiments, the dibasic ester blend comprises:

a diester of formula I:

a diester of formula II:

and

a diester of formula III:

R1 and/or R2 can individually comprise a hydrocarbon having from about 1to about 8 carbon atoms, typically, methyl, ethyl, propyl, isopropyl,butyl, isobutyl, n-butyl, isoamyl, hexyl, heptyl or octyl. In suchembodiments, the blend typically comprises (by weight of the blend) (i)about 15% to about 35% of the diester of formula I, (ii) about 55% toabout 70% of the diester of formula II, and (iii) about 7% to about 20%of the diester of formula III, and more typically, (i) about 20% toabout 28% of the diester of formula I, (ii) about 59% to about 67% ofthe diester of formula II, and (iii) about 9% to about 17% of thediester of formula III. The blend is generally characterized by a flashpoint of 98° C., a vapor pressure at 20° C. of less than about 10 Pa,and a distillation temperature range of about 200-300° C. Mention mayalso be made of Rhodiasolv® RPDE (Rhodia Inc., Cranbury, N.J.),Rhodiasolv® DIB (Rhodia Inc., Cranbury, N.J.) and Rhodiasolv® DEE(Rhodia Inc., Cranbury, N.J.).

In certain other embodiments, the dibasic ester blend comprises:

a diester of the formula IV:

a diester of the formula V:

and, optionally,

a diester of the formula VI:

R1 and/or R2 can individually comprise a hydrocarbon having from about 1to about 8 carbon atoms, typically, methyl, ethyl, propyl, isopropyl,butyl, isobutyl, n-butyl, isoamyl, hexyl, heptyl, or octyl. In suchembodiments, the blend typically comprises (by weight of the blend) (i)from about 5% to about 30% of the diester of formula IV, (ii) from about70% to about 95% of the diester of formula V, and (iii) from about 0% toabout 10% of the diester of formula VI. More typically, the blendtypically comprises (by weight of the blend): (i) from about 6% to about12% of the diester of formula IV, (ii) from about 86% to about 92% ofthe diester of formula V, and (iii) from about 0.5% to about 4% of thediester of formula VI.

Most typically, the blend comprises (by weight of the blend): (i) about9% of the diester of formula IV, (ii) about 89% of the diester offormula V, and (iii) about 1% of the diester of formula VI. The blend isgenerally characterized by a flash point of 98° C., a vapor pressure at20° C. of less than about 10 Pa, and a distillation temperature range ofabout 200-275° C. Mention may be made of Rhodiasolv® IRIS (Rhodia Inc.,Cranbury, N.J.) and Rhodiasolv® DEE/M (Rhodia Inc., Cranbury, N.J.)

In another embodiment, the solvent blend can include other solvents,including but not limited to aliphatic or acyclic hydrocarbons solvents,halogenated solvents, aromatic hydrocarbon solvents, cyclic terpenes,unsaturated hydrocarbon solvents, halocarbon solvents, polyols, alcoholsincluding short chain alcohols, ketones or mixtures thereof.

The dioxane compound utilized as the alternative solvent or in thealternative solvent blend as described herein includes those of formula(I), below:

in which: R6 and R7, which are identical or different, representhydrogen or a C1-C14 group or radical. In one embodiment, R6 and R7 areindividually selected from an alkyl group, alkenyl group or phenylradical. In some embodiments, “n” is an integer of 1, 2, 3, 4, 5, 6, 7,8, 9, 10, 11 or 12. Typically, “n” is an integer from about 1 to 4. Moretypically, “n” is 1 or 2.

In one particular embodiment, R6 and R7 are radicals individuallyselected from methyl, ethyl, n-propyl, isopropyl or isobutyl radical.

In one embodiment the dioxolane compound is of formula (I) is2,2-dimethyl-1,3-dioxolane-4-methanol. In another embodiment, thedioxolane compound of formula (I) is2,2-diisobutyl-1,3-dioxolane-4-methanol (also known by the acronym IIPG,for the synonym 1-isobutyl-isopropylidene glycerol).

Hydrophobic polymer bundles were suspended in a green ecofriendlysolvent such as Rhodiasolv IRIS, RPDE, Augeo, DIB etc. This slurry ofhydrophobic polymer bundles converts the delivery system into a liquidform that can easily be pumped and metered into tanks. This also removesthe hazard associated with the handling of fibers while improvingtransportation/storage profile.

EXPERIMENTS Example 1 Solvent Screening

Hydrophobic polymer fibers of <10 mm length and <50 μm diameter with ahigh aspect ratio (L/D=150) were used. 1 g of the fibers was placed in20 mL glass vials and occupied a uncompressed volume of 10-15 mL. 10 gof a range of solvents Rhodiasolv IRIS (branched dibasic esters ofglutaric and adipic acid), RPDE (linear dibasic esters of glutaric,succinic, and adipic acid), Augeo (glyceryl ketal), Polarclean (etheramide), ADMA (alkyl dimethyl amide), DIB (Diisobutyl ester), and DEE(linear diethyl ester mix) were added as shown in middle row of FIG. 1(10%). The solvents barely cover the fiber mass which behaves as a wetwooly mass that is not pumpable. Further addition of solvent to thevials (bottom row of FIG. 1) dilutes the hydrophobic polymerconcentration to merely 5% and the fibers occupy the entire volume ofthe vial. The fiber suspension is still a plug at this concentrationthat would only be pumped with difficulty with solvent drainage throughthe mass. One can still visualize clusters of fibers in white aggregatessuggesting poor dispersion of individual fibers. This exampledemonstrates that staple fibers as supplied cannot be suspended at highconcentrations in a liquid medium.

Example 2 Hydrophobic Polymer Fiber Bundles

Hydrophobic polymer staple fibers were compacted with native guar (Higum1122) as binder. 15 g of a viscous Higum 1122 solution at aconcentration of 1% w/w was added to 5 g of hydrophobic polymer staplefibers. The two were mixed together into a paste. The paste was thenrolled into spherical bundles (10-12 mm) in diameter. These bundles werethen dried in a convection oven at 65° C. overnight. Referring to FIG.2, a significant reduction in volume occupied was achieved whileimproving the handling characteristics. These pellets can bepneumatically conveyed.

These pellets were then added to water with stirring such that theconcentration of the hydrophobic polymer fibers in the final suspensionwas ˜1%. Simple mixing without the need for specialized equipment allowseasy hydration of the bundles. Hydrophobic polymer fibers were dispersedthrough the bulk of the suspension as shown in FIGS. 3( a) and 3(b). Thesuspension was observed to be stable over several weeks.

Example 3 Increasing Hydrophobic Polymer Fiber Bundle Density

The density of the fiber bundles and the size can be further reduced andoptimized as shown in FIGS. 4( a)-4(d). FIG. 4( a) shows a paste polymerwith 1% binder solution, dryed at 65° C. overnight. FIG. 4( b) shows adry polymer fiber and binder polymer (10%) mixed with a paste with 1%binder solution, dryed at 65° C. overnight. FIG. 4( c) shows a drypolymer fiber and binder polymer (10%) mixed with a paste with 1% bindersolution, rolled into cylinders, dryed at 65° C. overnight. FIG. 4( d)shows a dry polymer fiber and binder polymer (10%) mixed with a pastewith 1% binder solution, rolled into cylinders, dryed at 65° C.overnight, which are cut into pieces having staple lengths of about 6-8mm. Increasing the guar binder concentration cannot be easily achieveddue to the high viscosity of the 1% guar solution. The hydrophobicpolymer fibers bundles as described in Example 2 are shown in FIG. 4(a). In order to reduce the bundles size dry guar powder and hydrophobicpolymer fibers were mixed and then 1% solution of guar was added toyield a more viscous paste and adhesive binder content. The hydrophobicpolymer fibers could now be rolled into a more compact sphere, asillustrated in FIG. 4( b).

In order to further increase the density (packing fraction) the viscouspaste so prepared was rolled into cylinders (FIG. 4( c); approx. 4 mmdiameter) and dried in a convection oven. This aligns the fibers andallows for greater degree of packing and density. These were thenfurther cut into 6-8 mm cylinders (i.e., staple length). This wouldallow for more efficient packing into a slurry.

Example 4 Hydrophobic Polymer Bundles in Solvent Suspensions

hydrophobic polymer bundles were then suspended in solvents screened inExample 1. A pregel of clay in solvent was prepared to provide viscosityand suspending properties to the solvent. Several clays were screenedand Benathix® from Elementis was found to be the most effective for thesolvents as described herein. The clay concentration was 4% (as shown inFIG. 5( a)), and 2% (as shown in FIGS. 5( b), 5(c)). The higher densitycylinders as shown in FIG. 5( b) can be packed at higher concentrationsw/w into the solvent-clay medium. This suspension can flow as shown inFIG. 5( c) in contrast with the fibers alone as shown in FIG. 1. Thissuspension can be hydrated in water.

It should be apparent that embodiments and equivalents other than thoseexpressly discussed above come within the spirit and scope of thepresent invention. Thus, the present invention is not limited by theabove description but is defined by the appended claims.

What is claimed is:
 1. A method of preparing dispersible fiber bundlescomprising contacting a rheology-modifying binder with at least two ormore fibers to form a binder-fiber mixture, and imparting force to thebinder-fiber mixture to compact the binder-fiber mixture into a fiberbundle, wherein the rheology-modifying binder is selected from at leastone guar, at least one derivatized guar, at least one modifiedcellulose, at least one acrylate, at least one viscoelastic surfactant,or any combination thereof.
 2. The method of claim 1 wherein therheology-modifying binder is at selected from at least one guar,
 3. Amethod of preparing dispersible fiber bundles comprising: contacting arheology-modifying binder with at least two or more fibers to form abinder-fiber mixture; imparting force to the binder-fiber mixture tosubstantially orient the at least two fibers in a first direction,thereby forming a fiber bundle; and severing the fiber bundle into twoor more shorter length fiber bundles.
 4. The method of claim 3 whereinthe rheology-modifying binder is selected from at least one guar, atleast one derivatized guar, at least one modified cellulose, at leastone acrylate, at least one viscoelastic surfactant, or any combinationthereof.
 5. The method of claim 3 wherein the at least two fibers areoriented in a substantially longitudinal direction.
 6. The method ofclaim 3 wherein the at least two fibers are selected from celluloseacetate, polyamide, PLA, PGA, PEEK, acrylic, polyester, glass, metal,inorganic, poly-3-hydroxybutyrate (PHB), polyhydroxyalkanoates (PHA),Polyamide 11 (PA 11) or any combination thereof.
 7. A method ofpreparing a dispersible fiber bundle slurry comprising: contacting arheology-modifying binder to at least two or more fibers to form abinder-fiber mixture, imparting force to the binder-fiber mixture tosubstantially orient the at least two fibers in a first direction,thereby forming a fiber bundle; and contacting the fiber bundle with asolvent blend, the solvent blend comprising at least one of thefollowing components: a) dialkyl methylglutarate; b) a first blend of:dialkyl methylglutarate, dialkyl ethylsuccinate and, optionally, dialkyladipate; c) a second blend of: dialkyl adipate, dialkyl glutarate anddialkyl succinate; d) a dioxolane compound of formula I:

wherein R6 and R7, which may be identical or different, is individuallya hydrogen, an alkyl group, an alkenyl group, or a phenyl group, whereinn is an integer of from 1 to 10; and e) a compound or mixture ofcompounds having formula (II):R₃OOC-A-CONR₄R₅  (II), wherein R₃ is a group chosen from saturated orunsaturated, linear or branched, optionally cyclic, optionally aromatichydrocarbon-based groups comprising an average number of carbon atomsranging from 1 to 36; wherein R₄ and R₅, which are identical ordifferent, are groups chosen from saturated or unsaturated, linear orbranched, optionally cyclic, optionally aromatic, optionally substitutedhydrocarbon-based groups comprising an average number of carbon atomsranging from 1 to 36, it being possible for R₄ and R₅ to optionallytogether form a ring, that is optionally substituted; and wherein A is alinear or branched divalent alkyl group comprising an average number ofcarbon atoms ranging from 2 to
 12. 8. The method of claim 7 wherein theat least two fibers are oriented in a substantially longitudinaldirection.
 9. The method of claim 7 further comprising: severing thefiber bundle into two or more shorter length fiber bundles; orcompacting the fiber bundle.
 10. The method of claim 7 wherein the atleast two fibers are selected from cellulose acetate, polyamide, PLA,PGA, PEEK, acrylic, polyester, glass, metal, inorganic,poly-3-hydroxybutyrate (PHB), polyhydroxyalkanoates (PHA), Polyamide 11(PA 11) or any combination thereof.
 11. A fiber bundle comprising: atleast two polymer fibers; and a rheology-modifying binder comprising atleast, one guar, at least one derivatized guar, at least one modifiedcellulose, at least one cellulose, at least one acrylate, at least oneviscoelastic surfactant, or any combination thereof, wherein the fibersare treated with an effective amount of the binder to enhance thecohesion of the fiber bundle.
 12. The fiber bundle of claim 11 whereinthe at least two polymer fibers is selected from cellulose acetate,polyamide, PLA, PGA, PEEK, acrylic, polyester, glass, metal, inorganic,poly-3-hydroxybutyrate (PHB), polyhydroxyalkanoates (PHA), Polyamide 11(PA 11) or any combination thereof.
 13. A fiber bundle slurrycomprising: a fiber bundle comprising: a) at least two polymer fibers;and b) a rheology-modifying binder comprising at least one guar, atleast one derivatized guar, at least one modified cellulose, at leastone cellulose, at least one acrylate, at least one viscoelasticsurfactant, or any combination thereof, wherein the fibers are treatedwith an effective amount of the binder to enhance the cohesion of thefiber bundle; a solvent blend comprising at least one of the followingcomponents: a) dialkyl methylglutarate; b) a first blend of: dialkylmethylglutarate, dialkyl ethylsuccinate and, optionally, dialkyladipate; c) a second blend of: dialkyl adipate, dialkyl glutarate anddialkyl succinate; d) a dioxolane compound of formula I:

wherein R6 and R7, which may be identical or different, is individuallya hydrogen, an alkyl group, an alkenyl group, or a phenyl group, whereinn is an integer of from 1 to 10; and e) a compound or mixture ofcompounds having formula (II):R₃OOC-A-CONR₄R₅  (II), wherein R₃ is a group chosen from saturated orunsaturated, linear or branched, optionally cyclic, optionally aromatichydrocarbon-based groups comprising an average number of carbon atomsranging from 1 to 36; wherein R₄ and R₅, which are identical ordifferent, are groups chosen from saturated or unsaturated, linear orbranched, optionally cyclic, optionally aromatic, optionally substitutedhydrocarbon-based groups comprising an average number of carbon atomsranging from 1 to 36, it being possible for R₄ and R₅ to optionallytogether form a ring, that is optionally substituted; and wherein A is alinear or branched divalent alkyl group comprising an average number ofcarbon atoms ranging from 2 to
 12. 14. The fiber bundle slurry of claim13 wherein the at least two polymer fibers is selected from celluloseacetate, polyamide, PLA, PGA, PEEK, acrylic, polyester, glass, metal,inorganic, poly-3-hydroxybutyrate (PHB), polyhydroxyalkanoates (PHA),Polyamide 11 (PA 11) or any combination thereof.
 15. The fiber bundle ofclaim 11 wherein the polymer fibers have an average staple length of atleast 4 mm.
 16. The fiber bundle of claim 11 wherein the polymer fibershave an average staple length of at least 10 mm.
 17. The fiber bundle ofclaim 11 wherein the polymer fibers have an average staple length of atleast 15 mm.
 18. The fiber bundle slurry of claim 13 wherein the polymerfibers have an average staple length of at least 4 mm.
 19. The fiberbundle slurry of claim 13 wherein the polymer fibers have an averagestaple length of at least 10 mm.
 20. The fiber bundle slurry of claim 13wherein the polymer fibers have an average staple length of at least 15mm.